How to troubleshoot and fix dead device and diagnose the fault (Tektronix 485)
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- čas přidán 22. 09. 2022
- Step by step repairing of oscilloscope, making use of manufacture service manual covering fault diagnosing principles and testing strategies.
- Věda a technologie
Great video tutorial. Thank you.
Wow, thanks for doing this in English too! Great video!
Thanks for your good feedback 👍
The fault-finding system built into the 485 is ingenious, a real engineering marvel in my opinion. Those comb connectors that join different boards to the power supply board should have been carried over to all their later 'scopes. Once you know which rail is shorted....They can be disconnected while monitoring the short resistance on the power board, when the connector to the board with the short, likely as you say a tantalum cap, is disconnected you'll see the resistance of the winding for that rail. There is a resistor on one of the boards (I'm sorry I can't recall which) which is carrying too much current and tends to fail. Just look for the cooked one.
Thanks for the note, yes you are absolutely correct, in fact the circuit design and board finishing on this older Tektronix oscilloscope series is amazing and so reliable they last for many years with no issues, this one in the vedio 485 was produced around 1985 and till today they work like new (true old is gold) and the good thing they sold them with available comprehensive and helpful service manual.
@@saudautomation I don't think many of the current crop of 'scopes will still be around, and working, in 20 or 30 years time. They really don't build them like they used to!
I totally agree about the old service manuals (with schematics!), I really wish they were still a thing.
Thank you very much for your beautiful video and explanation.
I have the same device, a 485 but with a different problem, it only shows one point in the middle of the screen and it is not possible to do the horizontal deflection. Can you please help and say me where i should pay attention in the service manual and in the device ? For every answer, many thanks
You are very welcome,
You need to troubleshoot the sweep generator board and horizontal amplifier board, this are 2 separate boards, try as step one to remove and move the IC's from the socket then install fermly, check for visible dry solder if any resolder the points, tantalom capacitors can go short just go through them by multimeter, then try to start the device if no improvement then you will need to use another oscilloscope to trace the signals it is advisable to go through the circuit discription provided on the manual for both sweep board and horizontal amplifier board well be very helpful, I am sure you will fix the problem Tek485 is great oscilloscope is good to get it work. Good luck
Good video. I have the same issue, but the broken wire is too short to resolder. I can't find this transformer. Do you know the output voltage of this transformer?
The output voltage at secondary is 1 volt peak to peak, if cannot get original transformer you can use some closer transformer with in series resistor to adjust the output voltage. Good luck
Thank you for the reply. I am ordering a 1:1 audio transformer to see if it works. I will update once I get it.
You are very welcome,
But I afraid the audio transform won't work in this and might cause serious damage as it will not stepp down the ac and will not able to stand for high volt ac, what I suggest you look for some ac stepping down transformer as the primary windings needs to be designed to stand for ac high voltage, even if it is bigger in size try to accommodated in the side and use wires to connect. Then you can use potential divider to get 1 volt peak to peak at secondary.
Good advice. I will try that. Thanks